Electronic oil sensing methods currently include microwave line matching, microwave radar, ultraviolet intensity processing, density measurement, conductance measurement, magnetic sensor, and capacitive sensors. Each of the currently available methods has one or more drawbacks for use in low cost applications.
Microwave line matching requires (i) accurate calibration including calibration for temperature, (ii) a probe to be periodically cleaned, (iii) accurate installation and onsite calibration, and (iv) components that are very costly. Microwave radar requires accurate calibration and excessive data processing in addition to high costs due to components and expertise required to build the microwave radar. Ultraviolet intensity processing requires regular cleaning, accurate calibration, and image processing. Further, ultraviolet intensity processing is installation dependent and requires high costs dues to components and the expertise required to build a system. Density measurement systems typically include changing an existing system for installation, are direction dependent, and have high costs associated with implementing the systems. Conductance measurement systems have very limited options for use with various liquids, are typically used for oil degradation or liquid level determination, and often produce false positives. Magnetic sensors are limited in the types of liquids available to be used with and are usually implemented to determine liquid levels. Capacitive sensors have low resolution, are typically implemented for determining liquid levels, and require changes to an existing system for installation.
Low cost sensors currently available have several drawbacks including, but not limited to, temperature sensitivity, liquid purity sensitivity, liquid flow sensitivity, residue build up, and low measurement resolution.